Gripping tool, gripping system, and method for manufacturing resin member

ABSTRACT

According to one embodiment, a gripping tool includes a gripper. The gripper is flexible and includes a first portion contacting a workpiece, a second portion opposing the first portion, and a granular material provided between the first portion and the second portion. The first portion includes a concave portion and a convex portion. The concave portion is recessed in a first direction. The first direction is from the first portion toward the second portion. The convex portion is provided around the concave portion and protrudes in a second direction. The second direction is the reverse of the first direction. The concave portion has a groove having a ring configuration recessed outward from a center of the gripper.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International ApplicationPCT/JP2018/033963, filed on Sep. 13, 2018. This application also claimspriority to Japanese Patent Application No. 2017-185393, filed on Sep.26, 2017. The entire contents of each are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a gripping tool, agripping system, and a method for manufacturing a resin member.

BACKGROUND

There is a gripping tool that includes a gripper having a granularmaterial provided in the interior of the gripper. The gripper of thegripping tool is caused to contact a workpiece; and the workpiece isgripped by solidifying the interior of the gripper by depressurizing. Ahigh gripping force of the gripping tool is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross-sectional view illustrating a grippingtool according to a first embodiment;

FIG. 2 is a perspective cross-sectional view illustrating a gripper ofthe gripping tool according to the embodiment;

FIGS. 3A to 3D are cross-sectional views illustrating the operation ofthe gripping tool according to the first embodiment;

FIGS. 4A to 4C are cross-sectional views illustrating the grippingmechanism of the gripping tool according to the first embodiment;

FIGS. 5A and 5B are cross-sectional views illustrating the operation ofa gripping tool according to a reference example;

FIGS. 6A to 6D are perspective views illustrating a method formanufacturing the gripping tool according to the first embodiment;

FIG. 7 is a perspective cross-sectional view illustrating a grippingtool according to a second embodiment;

FIG. 8 is a perspective cross-sectional view illustrating a grippingtool according to a third embodiment;

FIG. 9 is a perspective cross-sectional view illustrating a grippingtool according to a modification of the third embodiment; and

FIG. 10 is a schematic view illustrating the configuration of a grippingsystem according to a fourth embodiment.

DETAILED DESCRIPTION

According to one embodiment, a gripping tool includes a gripper. Thegripper is flexible and includes a first portion contacting a workpiece,a second portion opposing the first portion, and a granular materialprovided between the first portion and the second portion. The firstportion includes a concave portion and a convex portion. The concaveportion is recessed in a first direction. The first direction is fromthe first portion toward the second portion. The convex portion isprovided around the concave portion and protrudes in a second direction.The second direction is the reverse of the first direction. The concaveportion has a groove having a ring configuration recessed outward from acenter of the gripper.

Various embodiments are described below with reference to theaccompanying drawings.

The drawings are schematic and conceptual; and the relationships betweenthe thickness and width of portions, the proportions of sizes amongportions, etc., are not necessarily the same as the actual values. Thedimensions and proportions may be illustrated differently amongdrawings, even for identical portions.

In the specification and drawings, components similar to those describedpreviously or illustrated in an antecedent drawing are marked with likereference numerals, and a detailed description is omitted asappropriate.

First Embodiment

FIG. 1 is a perspective cross-sectional view illustrating a grippingtool 1 according to a first embodiment.

The gripping tool 1 according to the first embodiment includes a gripper10 that is flexible. A granular material 15 is provided in the interiorof the gripper 10.

Specifically, the gripper 10 includes a first portion 11 contacting aworkpiece to be gripped, and a second portion 12 opposing the firstportion 11. The first portion 11 and the second portion 12 includeflexible materials such as a silicone resin, a rubber material, anacrylic resin, etc. The granular material 15 is provided in a firstspace SP1 between the first portion 11 and the second portion 12. Thegripper 10 is configured by, for example, bonding the first portion 11and the second portion 12 via a bonding agent. The first portion 11 andthe second portion 12 may be bonded by thermal compression bonding.

The outer perimeter of the first portion 11 and the outer perimeter ofthe second portion 12 are held by a holder 20. Thereby, the first spaceSP1 is separated from an external space. The holder 20 has, for example,a circular ring configuration. Because only the outer perimeter of thegripper 10 is held by the holder 20, the gripper 10 can deform insidethe holder 20 in the direction of a line connecting the first portion 11and the second portion 12.

The direction of the line connecting the first portion 11 and the secondportion 12 is, for example, along the vertical direction. The directionof the line connecting the first portion 11 and the second portion 12includes a first direction (up) from the first portion 11 toward thesecond portion 12, and a second direction (down) from the second portion12 toward the first portion 11. Hereinbelow, the description of theembodiments is performed using “vertical direction”, “up/above”, and“down/below” based on the positional relationship between the firstportion 11 and the second portion 12.

As an example, the holder 20 includes a first flange 21 and a secondflange 22. The first flange 21 abuts the outer perimeter lower surfaceof the first portion 11. The second flange 22 abuts the outer perimeterupper surface of the second portion 12. The gripper 10 is held byfastening the first flange 21 and the second flange 22 using a fastener23 such as a screw, etc.

FIG. 2 is a perspective cross-sectional view illustrating the gripper 10of the gripping tool 1 according to the embodiment.

The first portion 11 and the second portion 12 of the gripper 10 areillustrated as being separated in FIG. 2.

As illustrated in FIG. 2, the first portion 11 includes a concaveportion 11 r and a convex portion 11 p. The concave portion 11 r isrecessed upward and is provided at the center of the gripper 10. Theconvex portion 11 p protrudes downward and is provided around theconcave portion 11 r. The convex portion 11 p and the concave portion 11r are continuous with each other.

The upper surface of the concave portion 11 r contacts the secondportion 12. The convex portion 11 p is separated from the second portion12 in the vertical direction. In the gripping tool 1 illustrated in FIG.1 and FIG. 2, the first space SP1 is formed between the convex portion11 p and the second portion 12.

A second space SP2 which is surrounded with the concave portion 11 r andthe convex portion 11 p is formed below the first portion 11.Specifically, the top of the second space SP2 is covered with theconcave portion 11 r. The side of the second space SP2 is surroundedwith the convex portion 11 p. The bottom of the second space SP2 isopen. As described below, the second space SP2 is sealed from theexternal space by the workpiece to be gripped being positioned below thesecond space SP2.

As illustrated in FIG. 1 and FIG. 2, the gripper 10 further includes afirst port 31 and a second port 32. The first port 31 communicates withthe first space SP1. The second port 32 pierces the second portion 12and the concave portion 11 r of the first portion 11 and communicateswith the second space SP2. The diameter (the dimension in a directionperpendicular to the vertical direction) of the concave portion 11 r isless than the diameter of the second port 32. A first pipe 41 fordepressurizing the first space SP1 is connected to the first port 31. Asecond pipe 42 for depressurizing the second space SP2 is connected tothe second port 32.

In the gripping tool 1 according to the first embodiment, a groove Galso is provided in the concave portion 11 r. The groove G is recessedin the diametrical direction outward from the center of the gripper 10.In other words, the diametrical direction is a third direction from theconcave portion 11 r toward the convex portion 11 p and is perpendicularto the vertical direction. The groove G is provided in a ringconfiguration along a circumferential direction orthogonal to thediametrical direction.

In the example illustrated in FIG. 1, multiple grooves G are separatedfrom each other in the vertical direction. The diameter of the concaveportion 11 r changes periodically in the vertical direction. In otherwords, in the example illustrated in FIG. 1, a bellows-like structurethat is expandable/contractible in the vertical direction is provided inthe concave portion 11 r. For example, as illustrated in FIG. 2, athickness Th1 of the portion of the concave portion 11 r where thegroove G is provided is substantially the same as a thickness Th2 of theportion of the concave portion 11 r between the grooves G.

FIGS. 3A to 3D are cross-sectional views illustrating a gripping methodusing the gripping tool 1 according to the first embodiment.

FIGS. 3A to 3D illustrate an example in which a hemispherical workpieceis gripped by the gripping tool 1.

First, as illustrated in FIG. 3A, the position in the horizontaldirection of the gripper 10 and the position in the horizontal directionof a workpiece W are aligned. Then, the gripper 10 is lowered toward theworkpiece W; and the gripper 10 (the first portion 11) is caused tocontact the workpiece W.

The gripper 10 is flexible. Therefore, when the gripper 10 contacts theworkpiece W, the gripper 10 is pressed to spread outward as illustratedin FIG. 3B; and the gripper 10 deforms along the shape of the workpieceW. At this time, for example, the groove G is mashed in the verticaldirection. The second space SP2 which was open is sealed by theworkpiece W.

Continuing, the first space SP1 is depressurized via the first port 31.For example, the first space SP1 is depressurized to about 0.1atmosphere. Thereby, the granular material 15 in the first space SP1jams and solidifies as illustrated in FIG. 3C.

Then, the second space SP2 is depressurized via the second port 32. Forexample, the second space SP2 is depressurized to about 0.1 atmosphere.Thereby, the workpiece W is suctioned toward the second space SP2; andthe workpiece W is gripped. Continuing as illustrated in FIG. 3D, thegripper 10 is raised; and the workpiece W is lifted.

Subsequently, the workpiece W is moved to a prescribed position bymoving the gripping tool 1 in the horizontal direction. After moving theworkpiece W, the first space SP1 and the second space SP2 are opened tothe atmosphere. The gripping force is eliminated thereby; and theworkpiece W is released from the gripping tool 1.

By the method described above, the workpiece W to be gripped can betransferred to the prescribed position.

FIGS. 4A to 4C are cross-sectional views illustrating the grippingmechanism of the gripping tool 1 according to the first embodiment.

The gripper 10 of the gripping tool 1 is partially simplified in FIGS.4A to 4C.

In the gripping tool 1 according to the first embodiment as illustratedin FIG. 4A, the outer perimeter of the gripper 10 is held by the holder20. Accordingly, as illustrated in FIG. 4B, the gripper 10 can deformupward with respect to the workpiece W when the gripper 10 is caused tocontact the workpiece W.

Air is suctioned via the first port 31 and the second port 32 in thisstate. As illustrated in FIG. 4C, the contact area between the gripper10 and the workpiece W increases as the gripper 10 deforms furtherupward with respect to the workpiece W.

Thus, the gripping force when the workpiece W is gripped by the gripper10 can be increased by the gripper 10 being held to be deformable upwardwith respect to the workpiece W.

Effects of the first embodiment will now be described with reference toFIGS. 5A and 5B.

FIGS. 5A and 5B are cross-sectional views illustrating the grippingmethod using a gripping tool 1 r according to a reference example.

The gripping tool 1 r according to the reference example differs fromthe gripping tool 1 in that the groove G is not provided.

As illustrated in FIG. 5A and FIG. 5B, the concave portion 11 r bendstoward the center of the gripper 10 when the gripper 10 is caused tocontact the workpiece W by the gripping tool 1 r. There are cases wherethe second space SP2 which communicates with the second port 32 issealed thereby. When the second space SP2 is sealed by the gripper 10,the workpiece W is not suctioned to the gripper 10 even whendepressurizing via the second port 32. Even if the second space SP2 isnot sealed, there is a possibility that the workpiece W is not suctionedeasily because the concave portion 11 r bends and the second space SP2becomes narrow. As a result, the gripping force of the gripper 10decreases.

Conversely, in the gripping tool 1 according to the first embodiment,the groove G is provided in the concave portion 11 r. By providing thegroove G, the groove G is mashed in the vertical direction asillustrated in FIG. 3B even when a force is applied upward to theconcave portion 11 r. Therefore, the narrowing and the sealing of thesecond space SP2 by the concave portion 11 r can be suppressed. Thegripping force of the gripper 10 can be increased.

The number of the grooves G provided in the concave portion 11 r isarbitrary. It is desirable to provide multiple grooves G. By providingthe multiple grooves G, the concave portion 11 r can expand and contractmore in the vertical direction. Thereby, the bending of the concaveportion 11 r can be suppressed further; and the gripping force of thegripper 10 can be increased further.

FIGS. 6A to 6D are perspective views illustrating a method formanufacturing the gripping tool 1 according to the first embodiment.

Here, an example is described in which the gripping tool 1 ismanufactured using a mold unit 60 including a first mold 61, a secondmold 62, a third mold 63, and a fourth mold 64.

In FIG. 6C, the second mold 62 is not illustrated; and cross sections ofthe third mold 63 and the fourth mold 64 are illustrated.

The first mold 61 is a semicircular columnar member as illustrated inFIG. 6A. The first mold 61 includes a first curved portion 61 b and afirst planar portion 61 a parallel to a direction D1. The first curvedportion 61 b is provided at the side opposite to the first planarportion 61 a. The diameter of a first end portion 61 e at the directionD1 side of the first mold 61 is greater than the diameters of the otherportions.

A first groove 61 c which extends in the direction D1 is provided in thefirst planar portion 61 a. A first recess 61 d which is recessed in adirection crossing the direction D1 is provided in the first groove 61c. Multiple first recesses 61 d are provided to be separated from eachother in the direction D1. A second end portion 61 f at the sideopposite to the first end portion 61 e is linked smoothly to the firstcurved portion 61 b and the first groove 61 c.

The second mold 62 has a configuration similar to that of the first mold61. Namely, the second mold 62 includes a second planar portion 62 a anda second curved portion 62 b as illustrated in FIG. 6B. The diameter ofa third end portion 62 e at the direction D1 side of the second mold 62is greater than the diameters of the other portions. A second groove 62c is provided in the second planar portion 62 a; and multiple secondrecesses 62 d are provided in the second groove 62 c. A fourth endportion 62 f at the side opposite to the third end portion 62 e islinked smoothly to the second curved portion 62 b and the second groove62 c.

The first mold 61 and the second mold 62 are overlaid so that the firstplanar portion 61 a and the second planar portion 62 a contact eachother, and the first groove 61 c, the first end portion 61 e, and thesecond end portion 61 f respectively oppose the second groove 62 c, thethird end portion 62 e, and the fourth end portion 62 f.

As illustrated in FIG. 6C, the third mold 63 includes an extensionportion 63 a extending in the direction D1, and an outer perimeterportion 63 b which is provided around the extension portion 63 a andseparated from the extension portion 63 a. The extension portion 63 a ispositioned between the first groove 61 c and the second groove 62 c. Aportion of the first mold 61 and a portion of the second mold 62 aresurrounded with the outer perimeter portion 63 b. A ring-shapedprotrusion 63 c is provided at the surface of the extension portion 63a. Multiple protrusions 63 c are provided in the direction D1. Themultiple protrusions 63 c respectively oppose the multiple firstrecesses 61 d and the multiple second recesses 62 d.

The fourth mold 64 is a flat-plate shaped member. Multiple through-holes64 a which extend in the direction D1 are formed in the fourth mold 64.As illustrated in FIG. 6C and FIG. 6D, the first mold 61 and the secondmold 62 are placed between the third mold 63 and the fourth mold 64 inthe direction D1.

A gap is provided between the first mold 61, the second mold 62, thethird mold 63, and the fourth mold 64. The gripper 10 is made as a resinmember by injecting a resin via the through-holes 64 a into the gapbetween these molds and by curing the resin. For example, a siliconeresin or an acrylic resin can be used as the resin.

For example, the portion of the cured resin positioned between the thirdmold 63 and the first mold 61 and between the third mold 63 and thesecond mold 62 corresponds to the first portion 11. The portionpositioned between the protrusion 63 c and the first recess 61 d andbetween the protrusion 63 c and the second recess 62 d corresponds tothe groove G. The portion positioned between the fourth mold 64 and thefirst mold 61 and between the fourth mold 64 and the second mold 62corresponds to the second portion 12.

The gripping tool 1 illustrated in FIG. 1 and FIG. 2 is obtained byusing the holder 20 to fix the outer perimeter of the gripper 10 made inthe processes recited above and by providing the first port 31 and thesecond port 32.

Second Embodiment

FIG. 7 is a perspective cross-sectional view illustrating a grippingtool 2 according to a second embodiment.

In the gripping tool 2 according to the second embodiment, the rigidityof at least a portion of the concave portion 11 r is greater than therigidity of the convex portion 11 p.

For example, as illustrated in FIG. 7, the thickness of the portion ofthe concave portion 11 r along the vertical direction is greater thanthe thickness of the convex portion 11 p. Or, the rigidity of thematerial included in at least a portion of the concave portion 11 r maybe higher than the rigidity of the material included in the convexportion 11 p. Or, another member may be adhered to at least a portion ofthe concave portion 11 r. These methods can be combined as appropriate.

By setting the rigidity of at least a portion of the concave portion 11r to be greater than the rigidity of the convex portion 11 p, theconcave portion 11 r does not deform easily when the gripper 10 iscaused to contact the workpiece. As a result, the gripper 10 does notseal the second space SP2 easily. Thereby, in the embodiment as well,the gripping force can be improved similarly to the first embodiment.

Third Embodiment

FIG. 8 is a perspective cross-sectional view illustrating a grippingtool 3 according to a third embodiment.

The gripping tool 3 according to the third embodiment includes aring-shaped member 50 fixed to the concave portion 11 r. The ring-shapedmember 50 is provided along the concave portion 11 r. For example, theexterior form of the ring-shaped member 50 is circular. The directionoutward from the center of the ring-shaped member 50 is parallel to thedirection outward from the center of the gripper 10. For example, thering-shaped member 50 is fixed to the concave portion 11 r by a bondingagent.

In the example illustrated in FIG. 8, multiple ring-shaped members 50are separated from each other along the vertical direction. The rigidityof the ring-shaped member 50 is higher than the rigidity of the firstportion 11. By fixing the ring-shaped member 50 having the high rigidityto the concave portion 11 r, the concave portion 11 r does not deformeasily when the gripper 10 contacts the workpiece. As a result, thegripper 10 does not seal the second space SP2 easily. Thereby, in theembodiment as well, the gripping force can be improved similarly to thefirst embodiment.

The ring-shaped member 50 may be fixed to the concave portion 11 rinside the gripper 10. The ring-shaped member 50 may be fixed to theconcave portion 11 r outside the gripper 10. When the ring-shaped member50 is provided inside the gripper 10, there is a possibility that thegranular material 15 may catch on the ring-shaped member 50; the fluidicproperties of the granular material 15 may decrease; and the grippingforce may decrease. Accordingly, it is favorable to fix the ring-shapedmember 50 to the concave portion 11 r outside the gripper 10.

Modification

FIG. 9 is a perspective cross-sectional view illustrating a grippingtool 3 a according to a modification of the third embodiment.

The gripping tool 3 a according to the modification further includes thegroove G similar to that of the gripping tool 1 according to the firstembodiment. The groove G is provided in the concave portion 11 r; andthe ring-shaped member 50 is provided along the groove G. At least aportion of the ring-shaped member 50 is provided inside the groove G. Inthe example illustrated in FIG. 9, the multiple ring-shaped members 50are provided respectively inside the multiple grooves G.

By providing the ring-shaped member 50 along the groove G, the concaveportion 11 r does not deform easily inward. The gripping force can beimproved further. Thus, the embodiments described above can beimplemented in combination as appropriate. For example, in the grippingtool 3 a, the rigidity of at least a portion of the concave portion 11 rmay be set to be higher than the rigidity of at least a portion of theconvex portion 11 p.

Fourth Embodiment

FIG. 10 is a schematic view illustrating the configuration of a grippingsystem 4 according to a fourth embodiment.

The gripping system 4 according to the embodiment includes the grippingtool 1, a pump unit 70, a pump unit 70 a, a controller 80, and atransfer robot 90.

The transfer robot 90 includes an arm 90 a. The arm 90 a includes, forexample, multiple joints; and the gripping tool 1 is mounted to the tipof the arm 90 a. The transfer robot 90 operates the arm 90 a, grips theworkpiece W, and transfers the workpiece W according to commands fromthe controller 80.

The pump unit 70 is connected to the first pipe 41 of the gripping tool1 illustrated in FIG. 1. The pump unit 70 a is connected to the secondpipe 42 of the gripping tool 1. The first space SP1 and the second spaceSP2 are depressurized and opened to the atmosphere by driving the pumpunits 70 and 70 a according to the commands from the controller 80.

The controller 80 includes a CPU (Central Processing Unit), ROM (ReadOnly Memory), nonvolatile flash memory, etc. Various calculationprocessing of the controller 80 is performed in the CPU. Various controlalgorithms, various constants, etc., necessary for the operation of thegripping system 4 are stored in the ROM. The transfer procedure of theworkpiece W, the transfer conditions, etc., are appropriately stored andsaved in the flash memory.

The controller 80 controls the operations of the pump unit 70, the pumpunit 70 a, and the transfer robot 90 by sending commands to the pumpunit 70, the pump unit 70 a, and the transfer robot 90 according to thetransfer procedure stored in the flash memory.

By including the gripping tool 1 having a high gripping force, thegripping system 4 can more reliably grip and transfer the workpiece W.The gripping system 4 may include the gripping tool 2, 3, or 3 a insteadof the gripping tool 1.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention. The above embodiments can be practiced incombination with each other.

What is claimed is:
 1. A gripping tool, comprising: a gripper, thegripper being flexible and including: a first portion contacting aworkpiece, a second portion opposing the first portion, and a granularmaterial provided between the first portion and the second portion, thefirst portion including: a concave portion recessed in a firstdirection, the first direction being from the first portion toward thesecond portion, and a convex portion, the convex portion being providedaround the concave portion and protruding in a second direction, thesecond direction being the reverse of the first direction, the concaveportion including a groove recessed outward from a center of thegripper, wherein a rigidity of at least a portion of the concave portionis higher than a rigidity of the convex portion.
 2. The tool accordingto claim 1, wherein the tool grips the workpiece by depressurizing aninterior of the gripper in a state in which the gripper is caused tocontact the workpiece.
 3. The tool according to claim 1, wherein thegroove is configured to be mashed in a line direction when the firstportion contacts the workpiece, and the line direction is along adirection connecting the first portion and the second portion.
 4. Thetool according to claim 1, wherein a plurality of the grooves isprovided in the first direction.
 5. The tool according to claim 1,wherein the gripper being deformable in a line direction connecting thefirst portion and the second portion.
 6. The tool according to claim 1,further comprising: a first port communicating with a first spacebetween the first portion and the second portion, the first port beingconfigured to be connected to a first pipe for depressurizing the firstspace, and a second port communicating with a second space surroundedwith the concave portion and the convex portion, the second port beingconfigured to be connected to a second pipe for depressurizing thesecond space.
 7. A gripping system, comprising: a robot mechanismincluding an arm; and the gripping tool according to claim 1 mounted toa tip of the arm.
 8. A gripping tool, comprising: a gripper, the gripperbeing flexible and including: a first portion contacting a workpiece, asecond portion opposing the first portion, and a granular materialprovided between the first portion and the second portion, the firstportion including: a concave portion recessed in a first direction, thefirst direction being from the first portion toward the second portion,and a convex portion, the convex portion being provided around theconcave portion and protruding in a second direction, the seconddirection being the reverse of the first direction, the concave portionincluding a groove recessed outward from a center of the gripper, andfurther comprising a ring-shaped member, the groove having a ringconfiguration and being provided along a circumferential direction, thecircumferential direction is orthogonal to a direction from the centerof the gripper toward an outer perimeter of the gripper, the ring-shapedmember being provided along the groove, a rigidity of the ring-shapedmember being higher than a rigidity of the convex portion, at least aportion of the ring-shaped member being provided inside the groove.
 9. Agripping tool, comprising: a gripper, the gripper being flexible andincluding a first portion contacting a workpiece, a second portionopposing the first portion, and a granular material provided between thefirst portion and the second portion, the first portion including: aconcave portion recessed in a first direction, the first direction beingfrom the first portion toward the second portion, and a convex portion,the convex portion being provided around the concave portion andprotruding in a second direction, the second direction being the reverseof the first direction, a rigidity of at least a portion of the concaveportion being higher than a rigidity of the convex portion.
 10. The toolaccording to claim 9, wherein the tool grips the workpiece bydepressurizing an interior of the gripper in a state in which thegripper is caused to contact the workpiece.
 11. The tool according toclaim 9, wherein a thickness of the at least a portion of the concaveportion is greater than a thickness of the convex portion.
 12. Agripping tool, comprising: a gripper; and a ring-shaped member, thegripper being flexible and including: a first portion contacting aworkpiece, a second portion opposing the first portion, and a granularmaterial provided between the first portion and the second portion, thefirst portion including: a concave portion recessed in a firstdirection, the first direction being from the first portion toward thesecond portion, and a convex portion, the convex portion being providedaround the concave portion and protruding in a second direction, thesecond direction being the reverse of the first direction, thering-shaped member being fixed to the concave portion and having ahigher rigidity than the concave portion.
 13. The tool according toclaim 12, wherein the tool grips the workpiece by depressurizing aninterior of the gripper in a state in which the gripper is caused tocontact the workpiece.
 14. The tool according to claim 12, wherein thering-shaped member is provided externally to the gripper.
 15. The toolaccording to claim 12, wherein a plurality of the ring-shaped members isprovided in the first direction.
 16. A gripping tool, comprising:gripper, the gripper being flexible and including: a first portioncontacting a workpiece, a second portion opposing the first portion, anda granular material provided between the first portion and the secondportion, the first portion including: a concave portion recessed in afirst direction, the first direction being from the first portion towardthe second portion, and a convex portion, the convex portion beingprovided around the concave portion and protruding in a seconddirection, the second direction being the reverse of the firstdirection, the concave portion including a groove recessed outward froma center of the gripper, and further comprising a holder holding anouter perimeter of the convex portion and an outer perimeter of thesecond portion, inside the holder, the first portion and the secondportion being deformable in a line direction connecting the firstportion and the second portion.
 17. The tool according to claim 16, thefirst portion is more deformable in the first direction than the outerperimeter of the second portion held by the holder.
 18. A gripping tool,comprising: a gripper, the gripper being flexible and including: a firstportion contacting a workpiece, a second portion opposing the firstportion, and a granular material provided between the first portion andthe second portion, the first portion including: a concave portionrecessed in a first direction, the first direction being from the firstportion toward the second portion, and a convex portion, the convexportion being provided around the concave portion and protruding in asecond direction, the second direction being the reverse of the firstdirection, the concave portion including a groove recessed outward froma center of the gripper, wherein a port including a penetrating portionpenetrating the second portion and the concave portion, a firstdimension in one direction of the concave portion is longer than asecond dimension in the one direction of the penetrating portion, andthe one direction is perpendicular to the first direction.
 19. A methodfor manufacturing a resin member in a mold unit, the mold unitincluding: a first mold including a first planar portion and a firstcurved portion, the first curved portion being at a side opposite to thefirst planar portion and being parallel to a first direction, the firstplanar portion having a first groove extending in the first direction,the first groove including a first recess recessed in a directioncrossing the first direction, a second mold including a second planarportion and a second curved portion, the second curved portion being ata side opposite to the second planar portion and being parallel to thefirst direction, the second planar portion including a second grooveextending in the first direction, the second groove having a secondrecess recessed in a direction crossing the first direction, a thirdmold including an extension portion and a peripheral portion, theextension portion extending in the first direction and being positionedbetween the first groove and the second groove, the peripheral portionbeing provided around the extension portion and surrounding a portion ofthe first mold and a portion of the second mold, and a fourth mold, thefirst mold and the second mold being positioned between the third moldand the fourth mold in the first direction, the method comprising:injecting a resin into a gap between the first mold, the second mold,the third mold, and the fourth mold; and curing the resin.